In conventional treatment of bone fractures a plate is applied to a fractured bone so as to bridge the fracture. The plate is fixed to the bone by a plurality of screws. When the screws are tightened in the bone, they produce compressive stresses between the plate and the bone. Transmission of a functional load from the bone to the plate and back to the bone is achieved mostly by means of friction corresponding to the compressive stresses.
Usually the screws securing the plate to the bone engage both the near and the far wall of the bone cortex. The cortex receives its blood supply from the periosteum on its outer side and from the endosteum on the inner side. Compression of the plate and bone impedes the blood circulation of the cortex region under the plate. This is believed to increase the chances of infection, which is a major complication of operative fracture treatment.
Dead bone under the plate is in due course remodeled and revascularized. Remodeling starts at the periphery of the unperfused bone and proceeds towards the plate. Porosity within the remodelling bone persists for a long time and reduces bone strength. This situation requires keeping the plate on the bone longer than is needed for the fracture to heal. The use of long screws running first through the near cortex, then through the medullary canal, and through the far cortex may further interfere with blood supply of the fractured bone by cutting through larger blood vessels.